1. The problem statement, all variables and given/known data "Show that the variation of the potential between the plates of a large parallel plate capacitor remains the same if the air between the plates is replaced by a conductive medium." 2. Relevant equations E = σ/ϵ0 ; C = ϵ0A/d ' C = Q/V ; E = -dV/dx ; R = ρl/A 3. The attempt at a solution I've tried a lot of different things, substituting and replacing variables in the equation to try and get ρ to cancel out, but... I honestly have no idea.